Asplenium subglandulosum (Hook. & Grev.) Salvo, Prada & T.E.Díaz

Terrestrial or rupestral ferns. Rhizomes short, erect, bearing scales. Rhizome scales ovate with short filiform apices, 1–2 mm long, 0.3–0.5 mm wide, dark brown, clathrate with thick cell walls. Fronds 25–135 mm long or rarely to 190 mm long. Stipes 10–70 mm long or rarely to 120 mm long, pale brown, scaly at the very base, densely covered in colourless or pale brown glandular and non-glandular hairs; hairs 0.5–2 mm long. Rachises pale brown proximally, green distally, hairy. Laminae 1‑pinnate to deeply 1-pinnate-pinnatifid, narrowly elliptic or narrowly ovate, with a broad terminal segment, 15–95 mm long or rarely to 150 mm long, 6–26 mm wide, brownish-green, herbaceous, densely covered in colourless or pale brown glandular and non-glandular hairs. Primary pinnae in 2–7 pairs below a broad apical segment, not overlapping, ovate or broadly ovate or flabellate; the longest at or below the middle, 3–19 mm long, 2.5–13 mm wide; apices obtuse or rounded, margins entire or shallowly incised, bases unequally cuneate and stalked; the proximal pinnae often with an acroscopic lobe, sometimes divided almost to the midrib into a pair of lobes. Sori away from margins, 2–8 mm long, often becoming confluent at maturity; indusia absent. Mean spore size 39–42 μm long, 30–33 μm wide; perispores with broad ridges.

Asplenium subglandulosum is readily distinguished from all other New Zealand species of Asplenium by the dense covering of glandular and non-glandular hairs on both surfaces of the fronds, and the absence of indusia.

Asplenium subglandulosum occurs in crevices of open, sunny rock faces or in rocky ground under scrub. It grows in the crevices and fissures of limestone, greywacke, and schist. It is often found with Asplenium flabellifolium, Pellaea calidirupium, and species of Cheilanthes.

Asplenium subglandulosum is unusual among New Zealand species of the genus in that it has not been recorded hybridising with any other species. Its isolated phylogenetic position in Clade III of Schneider et al. (2004), in contrast to most New Zealand species, which occur in Clade V, may account for this.

n = 72 (Brownlie 1958).

Only tetraploid plants have been recorded in New Zealand, but in Australia Tindale & Roy (2002) reported diploid, tetraploid, and hexaploid plants.

Allan (1961) treated Asplenium subglandulosum in Pleurosorus, as P. rutifolius (see Taxonomy under Aspleniaceae). In Australia, Brownsey (1998) retained both P. rutifolius and P. subglandulosus as separate species, albeit "with considerable reservation". However, when treated in Asplenium, the name A. rutifolium based on Brown’s Grammitis rutifolius is preoccupied by A. rutifolium Kunze, and hence A. subglandulosum has priority.

Salvo et al. (1982) treated Pleurosorus papaverifolius (Kunze) Fée from Chile and Argentina, and P. hispanicus (Cosson) C.V.Morton from Spain and Morocco, as subspecies of Asplenium subglandulosum. We prefer to retain the different geographical populations as separate species, but the status of these taxa, including whether more than one is present in Australia, requires further investigation. Australasian populations show considerable variation in spore size and in the nature and abundance of their hairs (Brownsey 1998), and are known to be diploid, tetraploid, and hexaploid (Dawson et al. 2000; Tindale & Roy 2002), whereas Spanish populations are diploid (Salvo et al. 1982). Molecular evidence (Ohlsen et al. 2014) indicates sequence differences between the populations world-wide.

Gymnogramma alpina was described by Potts (1878) from a specimen collected by Mr Gray in the Upper Ashburton District, Canterbury, growing in rock crevices at 3000 ft. No original material has been located in CHR, K, or WELT, but there is one specimen in the Cheeseman Herbarium (AK 135877) labelled "Rangitata Valley, Southern Alps, T.H. Potts", and annotated "type of G. alpina Potts" in Cheeseman’s writing. There is no reason to doubt the authenticity of the specimen or label, it accords reasonably well with the protologue, and in the absence of any other original material is the presumed holotype of G. alpina. The material is clearly Asplenium subglandulosum.

Given (1972) analysed the ecological requirements of Asplenium subglandulosum (as Pleurosorus rutifolius) from all the then known New Zealand collections of the species. He also outlined the conservation status of the species at that time.